This sheet is about exposure to bimekizumab in pregnancy and while breastfeeding. This information is based on available published literature. It should not take the place of medical care and advice from your healthcare provider.
What is bimekizumab?
Bimekizumab is a medication that has been approved to treat moderate to severe plaque psoriasis. Bimekizumab has also been used to treat psoriatic arthritis, ankylosing spondylitis, and non-radiographic axial spondyloarthritis with signs of inflammation. A brand name for this medication is Bimzelx®.
Sometimes when people find out they are pregnant, they think about changing how they take their medication, or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take your medication. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy.
MotherToBaby has a sheet on psoriasis and psoriatic arthritis here https://mothertobaby.org/fact-sheets/psoriasis-and-pregnancy/ and a sheet on ankylosing spondylitis here https://mothertobaby.org/fact-sheets/ankylosing-spondylitis/
I am taking bimekizumab, but I would like to stop taking it before getting pregnant. How long does the drug stay in my body?
The time it takes the body to metabolize (process) medication is not the same for everyone. In healthy non-pregnant adults, it takes about 4½ months (around 138 days), on average, for most of the bimekizumab to be gone from the body.
I take bimekizumab. Can it make it harder for me to get pregnant?
Studies have not been done in humans to see if taking bimekizumab can make it harder to get pregnant. There was no effect on fertility in monkeys.
Does taking bimekizumab increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. Studies have not been done in humans to see if bimekizumab increases the chance of miscarriage.
Does taking bimekizumab increase the chance of birth defects?
Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. Studies have not been done in humans to see if bimekizumab increases the chance of birth defects. A study in monkeys did not report an increased chance for birth defects with exposure to doses up to 38 times the maximum recommended human dose.
Does taking bimekizumab in pregnancy increase the chance of other pregnancy-related problems?
Studies have not been done in humans to see if bimekizumab increases the chance of pregnancy-related problems including preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth). A study in monkeys did not report an increased chance for poor growth with exposure to doses up to 38 times the maximum recommended human dose.
Since bimekizumab might suppress the immune system of the person taking it, there is a theoretical concern that the same thing could happen to the baby if they are exposed during pregnancy. If someone has a weakened immune system they may be more likely to develop an infection from a live virus vaccine. Live vaccines contain a small amount of live virus. Inactivated vaccines do not contain live virus, so they cannot cause the disease they protect against. In the United States, rotavirus is the only live vaccine routinely given in the first year of life. Most babies can get inactivated vaccines in the first year of life. Talk with your child’s healthcare providers about your exposure to bimekizumab during pregnancy. They can talk with you about the vaccines your child should receive and the best time for your child to receive them.
Does taking bimekizumab in pregnancy affect future behavior or learning for the child?
Studies have not been done in humans to see if bimekizumab can increase the chance of behavior or learning issues for the child. A monkey study that followed the animals for 6 months after birth did not report an increased chance for changes in learning or behavior when exposed to doses up to 38 times the maximum recommended human dose during pregnancy.
Breastfeeding while taking bimekizumab:
Bimekizumab has not been studied for use during breastfeeding. Bimekizumab is a large protein molecule. Large protein molecules do not usually enter breast milk in high levels. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a male takes bimekizumab, could it affect fertility or increase the chance of birth defects?
Studies have not been done to see if bimekizumab could affect male fertility (ability to get partner pregnant) in humans or increase the chance of birth defects above the background risk. In general, exposures that fathers or sperm donors have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.
Please click here for references.
MotherToBaby is currently conducting a study looking at bimekizumab (Bimzelx®) and other medications used to treat psoriasis, psoriatic arthritis, ankylosing spondylitis, and non-radiographic axial spondyloarthritis in pregnancy. If you are interested in learning more about this study, please call 1-877-311-8972 or visit https://mothertobaby.org/join-study/.
OTIS/MotherToBaby encourages inclusive and person-centered language. While our name still contains a reference to mothers, we are updating our resources with more inclusive terms. Use of the term mother or maternal refers to a person who is pregnant. Use of the term father or paternal refers to a person who contributes sperm.